Artisan Spirit: Fall 2019

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ithout wanting to give the wrong impression, I’ve spent a lot of time staring into full (or partly-full) glasses in bars. As a lapsed chemist I tend to think about the composition of the contained liquids, so for whiskey, the main ingredient is, by concentration and usually by weight, water1, followed by alcohol. Then we have fermentation volatiles, minerals, wood extractives, with maturation-specific chemistry bringing in new entities such as dimethyl sulfoxide (DMSO) via the oxidation of dimethyl sulfide (DMS). So in principle, with a sufficiently comprehensive kit of pure chemical entities, we could take an empty glass and reconstitute something we know as whiskey. There are a few problems with this approach, apart from the obvious breach of the legal definitions of whiskey if we were to do this right now. Firstly, the kit of individual chemical compounds cannot be put together, at least not yet, as a complete list of compounds that can be found in a whiskey does not exist. Surely we know enough

about the composition of whiskey and the concentrations of the various components to make a good attempt, right? Well, perhaps, especially if we cheat a little and make appropriate extracts of, say, wood and peat for inclusion. These extracts can be considered to be groups of chemical compounds that, with satisfactory sensory performance, could preclude the need to understand the individual chemical components of a liquid recognizable as whiskey. Nevertheless, this spawns another question: What makes whiskey uniquely whiskey-ish? Alternatively, what is the minimum requirement for a portfolio of constituents that we must add to our empty glass to create a mixture that is undeniably whiskey in look and taste? How can this selection be made? This is more problematic than it appears. For instance, if we take a product that is understood to be 100 percent whiskey and had some way of removing half of the contained iso-amyl acetate, would the product still be whiskey? Instinct says yes, but there must come a point where

1  An alcohol-water mixture at 40% ABV has a density of around 0.95 g/ml. In a liter of 40% ABV at this density, the water content is 570 g (ca 31.7 M) and the alcohol content is 380 g (ca 8.3 M). Only at around 70% ABV are the molar concentrations of water and ethanol roughly equivalent. WWW.ART ISANSP IRITMAG.COM